Stabilized heating oil



STABILIZED HEA'HNG on.

Dilworth T. Rogers, Summit, and Harry W. Rudel, Roselle Park, N. 1., assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Application June 7, 1051, Serial No. 230,443

4 Claims. (Cl. 44-76) v This invention concerns a fuel oil composition particularly characterized by the inclusion of salts of phosphorous, arsenic, antimony or bismuth, maintained in the fuel oil by means of a suitable detergent. In a preferred embodiment, the invention concerns cracked fuel oil compositions containing sodium phosphate dissolved in the oil with the aid of a detergent such as sodium petroleum sulfonate. The fuel oil compositions of this invention are advantageous in that they are effectively stabilized by inclusion of the additives indicated.

The invention is of application to hydrocarbon mixtures generally known as fuel oils. Such hydrocarbon mixtures are employed in various burner systems as diesel fuels or as domestic and industrial heating oils. Fuel oils may be derived from petroleum by'a variety of methods including the straight distillation from crude petroleum oil and thermal or catalytic cracking of petroleum oil fractions. g

It has recently been observed that in the case of fuel oils consisting completely or in part of cracked stocks, these oils are characterized by undesirable instability. The instability is manifested by the formation of sediment after prolonged storage, particularly at elevated temperatures. Again, the instability of these fuel oils is evidenced by clogging of filters, orifices or fuel lines associated with burning systems in which the fuel oils are employed.

Consequently, this invention is of particular application to the preparation of fuel oil compositions which are made up at least in part of constituents derived from cracking operations. Such compositions may be effectively stabilized by employing additives herein disclosed.

Heating oils which may be stabilized by these additives are hydrocarbon mixtures of which more than about 10% consist of stocks derived from thermal or catalytic cracking operations. More precisely still, the base stocks may be characterized as petroleum fractions containing a proportion of cracked stocks greater than 10% and falling within A. S. T. M. specification D-975-48T for diesel fuel oils (grades Nos. 1-D to 4-D inclusive) and A. S. T. M. specification D-396-48T for fuel oils (grades Nos. 1 to 6 inclusive).

According to the present invention a small amount of a salt of certain of the group elements is employed in the fuel oil to be stabilized. Salts of phosphorus, arsenic, antimony and bismuth may be employed. In particular, the alkali metal, alkaline earth or ammonium salts of these particular metals are to be employed. The benefits of this invention may be obtained in part by dispersing the indicated salts in finely divided form so as to permit the salts to remain in suspension in the oil.

salts are maintained in oil solutionwith the aid of a suit- It has been found that an,

able solubilizer or detergent. I H alkali or alkaline earth metal sulfonate'which is oil s01 uble is effective in solubilizing the salts to be employed.

It is believed that a complex is formed between these oil soluble petroleum sulfonates and the salts of the group 5 elements serving to maintain the salts in solution. The preferred detergents are the alkali and alkaline earth metal sulfonates which areoil soluble. The oil'soluble petroleum sulfonates of sodium and calcium are particularly contemplated for use. 'In thecase of the alkaline earth metal sulfonates, the sulfonates of bariuin,-calcium, strontium and magnesium .are particularly preferred. Other detergents may be employed such as the metal soaps of the C16 to C24 fatty acids or'of naphthenic acids.

However, thesedetergents and other detergents which may be employed do not appear as effective as themetal petroleum sulfonates indicated. I

Of the salts of phosphorus, arsenic, antimony and hismuth, which may be employed, the preferred salts are the'salts of phosphorus, and particularly the sodium salts of phosphorus. Na'3PO4 presently appears to be the best of the sodium phosphates although NQZHPOd, NaHzPOi, NatPzOi and NasPOs have all been found to stabilize ,fuel oil.- The present invention will bedesc'ribed with particular reference to the use of tri-sodium' phospliate However, in the preferred practice of this invention, the

Na3PO4 since this is the preferred compound. Theanhydrous or hydrated forms of any of the described salts may be employed. I I

Only a very small proportion of a salt of arsenic, bismuth, antimony or phosphorus is to be included in the fuel oil. Expressing the proportion to be employed in terms of the anhydrous salts, the proportion to be used may vary from as little as about 0.0001 wtjpe'rcen't up to about 0.1 wt. percent. In the preferred embodiment of this invention the salt of phosphorus, arsenic, bismuth or' antimony is added to the fuel oil in the form of a complex with an alkali or alkaline earth metal petroleum sulfonate containing from about 2% to 20% of the salt of one of these metals; In this case about 0.0005 to 5.0 wt. percent of this complex may be employed. Preferably however, the indicated complex is used in weight proportions of about 0.005% to 0.02%, based on the weight of the oil. Since these proportions are based on the use of anhydrous salts of these metals in the event a hydrated salt is employed, the proportionsmust be compensated in accordance with the water of hydration.

While, as indicated, actual solutionof the selected salt in the oil is not necessary, it is preferred that the salt be dissolved in the fuel oil. A preferred procedure for incorporating the salt in heating oil is to prepare a complex with an oil soluble metallic sulfonate, e. g. of petroleum derivation and to dissolve the complex in mineral oil. This is accomplished by adding an aqueous solution of the salt, such as sodium phosphate to anoil soluble petroleum sulfonate, e. g. sodium or calcium sulfonate. Thereafter, the mixture is heated to a temperatureof about 300, F. to completely dehydrate it. The phosphate in this case is in actual solution in the oil and no separation of the salt from the oil occurs until a critical concentration of the phosphate in the sulfonate is reached. A sodium sulfonate concentrate (for example, 65% sulfonate, 35% oil) can absorb up to about 20% of Na'sPO4.12H20. A 30% concentration of calcium sub fonate' can absorb about the same quantity of the salt".

. 3 a A concentrate of the sodium sulfonate phosphate com plex prepared as indicated may then be employed in stabilizing fuel oil in the proportions formerly indicated.

In order to demonstrate the advantages and utility of the compositions of this invention, the following exemplary data are presented. In obtaining this data, a commercial heating oil was employed consisting of a blend of 20% to 30% catalytically cracked stock, 50% to 40% thermally cracked stock, and 30% virgin stock. Typical inspections of thistype of oil are as follows:

Grav., A. P.'I 34.1 Color, Tag Robinson 11% Flash; F. 158 Sulfur (per cent) 0.56 Aniline point, F.* 130 Neutralization No. 0.07 Dist. I. B; P. F.) 342 10% 420 50%" 484 9.0% 576 F; B. P. f 628 Carbon residue on 10% bottoms (per cent) 0.82

termined; bpth in the water phase and in the oil phase.

The resultsof'these tests are indicated in ,the following table:v

Heating oil stability tests employing s'ulfonatephosphate complex Mg. Insoluble per Rust Forma- Ratio, Concen- 600 g. tion 1 NB3PO4J2H O/ Na $5323;

Summate cent 16 Hrs. 14 Days Water Oil at 210 F. at 150 F. Phase Phase 0. 01 45 22 None None 0. 01 12 6 "410... D0. 0. 01 3 ..do Do. 0. 01 2 1 -.d0 D0. 0. 01 2 2 do Do. 0.01 2 2 do.. Do. 0. 0075 39 0. 0075 0. 0075 0. 0075 0. 0075 0. 0075 0. 005 0.52 0. 005 No additive None."

Mild steel strip maintained in contact with oil sample containing water for 52 days at toom temperature.

As. indicated in this table, the sodium phosphate maintained in the oil as a complex with sodium petroleum sulfonate was effective in all concentrations reported in stabilizing the fuel oil. sodium sulfonate complex was effective in eliminating the corrosive properties of the fuel oil in the water phase. It is particularly significant that these data show that sodium petroleum sulfonate alone is not effective in overcoming the instability of the fuel oil, but the combination of sodium phosphate and sodium petroleum sulfonate is required.

Other experiments have been conducted to determine the operability of other of the phosphorus salts. These experiments are set forth in the following table; in which the indicated phosphorus salts were tested in the commercial heating oil formerly identified. In each case the salt of phospohrus was added to the commercial heating In addition, the sodium phosphate, 7

. 4 oil in the form of a 50% concentrate of the phosphate salt in a lubricating oil vehicle.

Efiect of type of phosphate in complex 1 Salts used in equivalent concentrations.

As shown in this table each of the salts of phosphorus solubilized by sodium petroleum sulfonatewas efiective in stabilizing the heating oil as demonstrated by the 16 hour stability test.

Further tests were then conducted to determine the operability of employing a salt of one of the indicated group 5 metals in a finely dispersed form in the absence of a solubilizer or detergent. 0.004 wt. per cent of sodium phosphate dodecahydrate was dissolved in a small amount of water and added to the commercial heating oil formerly identified. This mixture was then heated while stirring and blowing with nitrogen to a temperature of 110 C. to drive off water. This served to leave the sodium phosphate in the heating oil in a finely dispersed form. The heating 'oil was then filtered and tested for stability employing the 16 hour stability test during which the oil was maintained at 210 F. In the case ofthe untreated oil at the end of the'stability test, 32 mg. of sediment was formedper 600g. of heating oil, and it was found that the color of the oil had degraded to a dark color and that the oil was turbidf In the case of the treated oil at the end of'the stability test, it was'found that only 16 mg. of sediment was formed per 600 g. of heating oil and that the color of the oil was light and the oil was clear. This data therefore shows that the finely dispersed salt, evenwithout the presence of a solubilizer, is at least partially effective in stabilizing the heating oil.

Other experiments were then conducted to demonstrate the utility and operability of employing other of the salts of group 5 metals. Again the same formerly identified heating oil was employed and each of the salts was added to the heating oil in the form of a complex Withsodium petroleum sulfonate. The data obtained is presented in the following table.

Sodium salts of oxygen acids from group V'EIGIHGIIIS Ratio: Cone. of I 16 Hrs. at Salt Still. Additive 210 Pet. (Wt. 1 (mg.I1isol. l

Sulfonato I Percent) 600 g.

Sodium Arsenite 0.16 .01 1 Sodium Arsenate 0. O8 0. 01 5 Sodium Bismuthate 0.14 .01 2S Sulionate Alone 0.00 30 Uninhibited 32 1 Salts used in equivalent concentrations.

ing oil may be enhanced by thisthree-c0mp0nent addi- It is particularly significant however tive composition. The data obtained is presented in the following table.

Sulfonate-phosphate complex in combination with barium isaoctyl phenol sulphide Sodium Petroleum Sultonate In accordance with this invention therefore, an alkali, alkaline earth metal or ammonium salt of phosphorus, antimony, arsenic or bismuth is to be incorporated in a cracked fuel oil in minor proportions. It is preferred to maintain one or more of these salts in the fuel oil by means of a solubilizer or a detergent. The preferred detergent constitutes an alkali or alkaline earth metal oil soluble petroleum sulfonate. In addition, it is particularly contemplated that other compounds may be included in the heating oil composition such as an alkaline earth metal alkyl phenol sulphide. It is apparent that other conventional additives ordinarily employed in a fuel oil may also be incorporated in the fuel oil compositions of this invention.

What is claimed is:

1. The process of stabilizing a heating oil constituting a petroleum fraction containing a proportion of cracked stocks greater than and falling within A. S. T. M. specification D-975-48T and A. S. T. M. specification D-396-48T, which comprises incorporating in the said petroleum fraction about 0.0001 to 0.1 weight percent of a compound selected from the group consisting of the alkali l Ratio: =0.20.

metal, alkaline earth and ammonium phosphates, arsenites, arsenates and bismuthates.

2. The process defined by claim 1 in which the said compound is incorporated in the heating oil by formation of a complex with a compound selected from the group consisting of the alkali metal and alkaline earth metal oil-soluble petroleum sulfonates.

3. A heating oil composition comprising a petroleum fraction containing a proportion of cracked stocks greater than 10% and falling within A. S. T. M. specification D-97548T and A. S. T. M. specification D-396-48T, and containing about 0.0005 to 5 weight percent of a compound selected from the group consisting of the oilsoluble alkali and alkaline earth metal petroleum sulfonates, and including about 2% to 20% of trisodium phosphate based on the said sulfonate.

4. A composition consisting essentially of a distillate heating oil containing more than about 10% of cracked constituents and containing about 0.0001 to 0.1 Weight percent of a compound selected from the group consisting of the alkali metal, alkaline earth metal, and ammonium phosphates, arsenites, arsenates, and bismuthates, together with a minor and solubilizing proportion of a compound selected from the group consisting of the alkali metal and alkaline earth metal oil-soluble petroleum sulfonates.

References Cited in the file of this patent UNITED STATES PATENTS 2,137,727 Quirke Nov. 22, 1938 2,301,370 Cook et al Nov. 10, 1942 2,409,687 Rogers et al Oct. 22, 1946 2,527,987 Caron et al. Oct. 31, 1950 2,623,016 Mertes Dec. 23, 1952 OTHER REFERENCES Monsanto Technical Bulletin, No. P-24, June 15, 1940, 6 pages, Monsanto Chemical Co., St. Louis, Mo.

Industrial and Engineering Chemistry, vol. 23, No. 5,

pages 470-474, Dec. 9, 1930., 

1. THE PROCESS OF STABILIZING A HEATING OIL CONSTITUTING A PETROLEUM FRACTION CONTAINING A PROPORTION OF CRACKED STOCKS GREATER THAN 10% AND FALLING WITHIN A. S. T. M. SPECIFICATION D-975-48T AND A. S. T. M. SPECIFICATION D-396-48T, WHICH COMPRISES INCORPORATING IN THE SAID PETROLEUM FRACTION ABOUT 0.0001 TO 0.1 WEIGHT PERCENT OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF THE ALKALI METAL, ALKALINE EARTH AND AMMONIUM PHOSPHATES ARSENITES, ARSENATES AND BISMUTHATES.
 2. THE PROCESS DEFINED BY CLAIM 1 IN WHICH THE SAID COMPOUND IS INCORPORATED IN THE HEATING OIL BY FORMATION OF A COMPLEX WITH A COMPOUND SELECTED FROM THE GROUP CONSISTING OF THE ALKAL METAL AND ALKALINE EARTH METAL OIL-SOLUBLE PETROLEUM SULFONATES. 